The present invention relates generally to a control system for controlling an actuator which regulates the state of a controlled apparatus so that the controlled apparatus assumes a desirable condition.
As one example of such control systems is known an automotive cruise control system for use in motor vehicles which is for the purposes of improving the response and following performance of the constant-speed control executed when the motor vehicle runs at a constant speed. As disclosed in the Japanese Patent Provisional Publication No. 62-85733, 62-241737 or 63-64833, the automotive cruise control system is arranged such that a state observer and an optimal feedback gain are respectively determined on the basis of a model predetermined through a system identification so that a state control amount is attained by the state observer in accordance with a control input amount (for example, throttle valve drive current) and a control output amount (for example, actual vehicle speed) so as to control the vehicle speed in accordance with a control input amount determined on the basis of the optimal feedback gain and the state control amount.
There is a problem which arises with this type of control system, however, in that the identification for determination of the model relating to the controlled system is required to be made in advance in designing stages and, because the models are different from each other between different types of motor vehicles, the system identification is required to be made for each of the different types of motor vehicles to result in being greatly troublesome. In addition, problems can be encountered in terms of difficulty of sufficiently suppressing affections from the characteristic variation of the controlled system so as to lead to inaccuracy of the model due to the controlled system characteristic variation. Further, although in an auto pilot control system for use in ships the model identification is made by means of an one-line operation so as to perform the above-mentioned control and a high-order system identification is required in order to realize high-accurate control, the on-line high-order model identification takes a relatively long time and is hence difficult to be employed for a controlled system in motor vehicles (for example) in which the control period is relatively short.